103b bh 2012f

From CSclasswiki
Jump to: navigation, search


On September 25, 2012 the entire CSC103 (How Computers Work) class gathered together in the Atrium at Smith College's Ford Hall. The intention of the meeting was to disassemble a collection of old PC computers in order to gain some understanding of their physical workings. The group started out with refreshments of coffee and pastries, and the professor, Dominique Thiebaut, proceeded to outline the procedure we were to follow for the session. As the computers were old, the participants were not required to handle the equipment with kid gloves! Taking them apart and an attempt at putting them back together again was to be done within the time period of 9 - 10:20 a.m. Realistically it was an hour, as refreshments and explanations took up some of the allotted time. With screwdrivers in hand, the students paired off to begin the project.

First Part

Joined by my partner Yuri, together we looked for the model number and make of the computer before taking the cover off. We found it on the bottom of the computer. Ours was a Windows XP Professional 1-2CPU by Dell.

We proceeded to unscrew the outer case to reveal the interior of the computer. Immediately one could see the fan motor, colored wires and chip boards. At the bottom of the picture one can see on the outside of the computer the power supply and the various ports. Our computer had an output of 210w. Also visible on the inside cover is the optical drive and the hard disk.

We then removed the fan motor, which had the heat sink underneath. As the picture shows Yuri then commenced to remove the heat sink. "In electronic systems, a heat sink is a passive component that cools a device by dissipating heat into the surrounding air." [1]

Second Part

Now we have gone deeper into the computer and we can see the motherboard. At a quick glance one can see the central processing unit (CPU), the RAM, and many points where cables and wires connect. To be more precise "A motherboard (sometimes alternatively known as the mainboard, system board, planar board or logic board[1]) is a printed circuit board (PCB) found in all modern computers which holds many of the crucial components of the system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals." [2]

As mentioned the motherboard held two vertical slots which contained the memory or RAM (Random Access Memory). The memory had a logo of an "M" in a circle and showed its capacity at 256MB9x2) MT 8V. Again Wikipedia gives us a simple definition of RAM. "Random-access memory (RAM) is a form of computer data storage. A random-access device allows stored data to be accessed in very nearly the same amount of time for any storage location, so data can be accessed quickly in any random order. In contrast, other data storage media such as hard disks, CDs, DVDs and magnetic tape, as well as early primary memory types such as drum memory, read and write data only in a predetermined order, consecutively, because of mechanical design limitations. Therefore the time to access a given data location varies significantly depending on its physical location." [3]

The cables or wires transfer data and connects the optical disk to the motherboard and the hard disk. It can be seen here on the left wrapped in a gray plastic, also known as a bus. [4]

Finally in this second part of our exploration we found the optical disk attached under the cover of the computer. Ours was specifically a DVD/CD rewritable drive by Plextor.


After removing the motor and fan in our first section we found the processor as seen on the left. It was an Intel Pentium 2.80GHZ/512/800.
  • "Central processing unit (CPU), an electronic circuit which executes computer programs, containing a processing unit and a control"
    • "Processing unit, in Von Neumann computer architecture, contains an arithmetic logic unit (ALU) and processor registers"


Once we found the hard disk (top right photo) we proceeded to open it up and found a rotating magnetic disk with an actuator arm (bottom right photo). "An HDD consists of one or more rigid ("hard") rapidly rotating discs (platters) coated with magnetic material. Magnetic heads arranged on a moving actuator arm read and write data to the surfaces. The read-write heads are supported on a thin layer of air inside the enclosed disk unit with only tiny gaps between the heads and the disk surface." [6]

Last but not least we have the crystals, one of which is pictured in the photo above. Our computer contained two crystals labeled D250F3H (shown above) and the other D143F3C. "A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, but other piezoelectric materials including polycrystaline ceramics are used in similar circuits.

Quartz crystals are manufactured for frequencies from a few tens of kilohertz to tens of megahertz. More than two billion crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. [7]

After examining, cataloging and photographing all the components, we then put the computer back together as best we could!


  1. http://en.wikipedia.org/wiki/Heat_sink
  2. http://en.wikipedia.org/wiki/Motherboard
    1. ^ Paul Miller. "Apple sneaks new logic board into whining MacBook Pros" (2006). Engadget. Retrieved 2008-10-23.
  3. http://en.wikipedia.org/wiki/Random-access_memory
  4. http://en.wikipedia.org/wiki/Bus_%28computing%29
  5. http://en.wikipedia.org/wiki/Processor
  6. http://en.wikipedia.org/wiki/Hard_disk_drive
  7. http://www.answers.com/topic/crystal-oscillator